Accueil du siteDoctoratAllemagneClimate change in Libya and desertification of Jifara Plain : using geographical information system and remote sensing techniques

Johannes Gutenberg Universität Mainz (2005)

Climate change in Libya and desertification of Jifara Plain : using geographical information system and remote sensing techniques

Tantawi, Attia Mahmoud Mohamed el-

Titre : Climate change in Libya and desertification of Jifara Plain : using geographical information system and remote sensing techniques

Auteur : Tantawi, Attia Mahmoud Mohamed el-

Université de soutenance : Johannes Gutenberg Universität Mainz

Grade : Doktorgrade 2005

Résumé partiel The study was arranged to manifest its objectives through preceding it with an introduction.
Particular attention was paid in the second part to detect the physical settings of
the study area, together with an attempt to show the climatic characteristics in Libya. In the
third part, observed temporal and spatial climate change in Libya was investigated through
the trends of temperature, precipitation, relative humidity and cloud amount over the periods
(1946-2000), (1946-1975), and (1976-2000), comparing the results with the global
scales. The forth part detected the natural and human causes of climate change concentrating
on the greenhouse effect. The potential impacts of climate change on Libya were examined
in the fifth chapter. As a case study, desertification of Jifara Plain was studied in
the sixth part. In the seventh chapter, projections and mitigations of climate change and
desertification were discussed. Ultimately, the main results and recommendations of the
study were summarized.
In order to carry through the objectives outlined above, the following methods and
approaches were used : a simple linear regression analysis was computed to detect the
trends of climatic parameters over time ; a trend test based on a trend-to-noise-ratio was
applied for detecting linear or non-linear trends ; the non-parametric Mann-Kendall test for
trend was used to reveal the behavior of the trends and their significance ; PCA was applied
to construct the all-Libya climatic parameters trends ; aridity index after Walter-Lieth was
shown for computing humid respectively arid months in Libya ; correlation coefficient,
(after Pearson) for detecting the teleconnection between sun spot numbers, NAOI, SOI,
GHGs, and global warming, climate changes in Libya ; aridity index, after De Martonne, to
elaborate the trends of aridity in Jifara Plain ; Geographical Information System and Remote
Sensing techniques were applied to clarify the illustrations and to monitor desertification
of Jifara Plain using the available satellite images MSS, TM, ETM+ and Shuttle
Radar Topography Mission (SRTM). The results are explained by 88 tables, 96 figures and
10 photos.
Temporal and spatial temperature changes in Libya indicated remarkably different annual
and seasonal trends over the long observation period 1946-2000 and the short observation
periods 1946-1975 and 1976-2000. Trends of mean annual temperature were positive
at all study stations except at one from 1946-2000, negative trends prevailed at most
stations from 1946-1975, while strongly positive trends were computed at all study stations from 1976-2000 corresponding with the global warming trend. Positive trends of mean
minimum temperatures were observed at all reference stations from 1946-2000 and 1976-
2000, while negative trends prevailed at most stations over the period 1946-1975. For
mean maximum temperature, positive trends were shown from 1946-2000 and from 1976-
2000 at most stations, while most trends were negative from 1946-1975. Minimum temperatures
increased at nearly more than twice the rate of maximum temperatures at most
stations. In respect of seasonal temperature, warming mostly occurred in summer and autumn
in contrast to the global observations identifying warming mostly in winter and
spring in both study periods.
Precipitation across Libya is characterized by scanty and sporadically totals, as well as
high intensities and very high spatial and temporal variabilities. From 1946-2000, large
inter-annual and intra-annual variabilities were observed. Positive trends of annual precipitation
totals have been observed from 1946-2000, negative trends from 1976-2000 at most
stations. Variabilities of seasonal precipitation over Libya are more strikingly experienced
from 1976-2000 than from 1951-1975 indicating a growing magnitude of climate change
in more recent times.